The medical suturing needle used to suture living tissues is generally curved from the needle tip to the proximal end through the trunk portion. The curved shape has substantially the same curvature radius over the entire length, and is formed to a shape (an angle) such as ½ circle (180 degrees), ⅜ circle (135 degrees), or ¼ circle (90 degrees). Plural types of medical suturing needles having different thickness and different length have been proposed, which have a curved shape with different curvature radius for every type.
When manufacturing the medical suturing needle curved in the above manner, an art described in Patent Document 1 is known for the bending method of curving the raw material of a shaft rod-shape. In this art, the shaft rod-shaped raw material is curved by inserting the raw material between a circular column shaped bending roll and a belt having flexibility as can be pressure contacted and wound to the outer circumference of the bending roll, bending the raw material along the outer circumferential surface of the bending roller by winding the raw material with the bending roll and the belt, and thereafter, discharging the bent raw material by rewinding.
As described in Patent Document 2, a bending apparatus including a cylindrical winding roll that defines the curved shape of the medical suturing needle, an auxiliary roll that pressure contacts such winding roll, and a metal belt arranged between the winding roll and the auxiliary roll is used, so that the inserted linear needle-shaped raw material can be bent by inserting the linear needle-shaped raw material between the winding roll and the metal belt and rotating the winding roll by a predetermined angle in a clockwise direction. The winding roll is then rotated in the counterclockwise direction so that the curved medical suturing needle can be taken out.
A bi-curve needle or a medical suturing needle mainly used in the opthalmologic surgery is curved with different curvature radii for the needle tip portion and for the trunk portion. The art described in Patent Document 3 is proposed as one method of bending such medical suturing needle.
In the art described in Patent Document 3, the bending work is performed on the linear needle-shaped raw material, which is formed to a predetermined cross-sectional shape in advance, over a predetermined range from one end side at the largest curvature radius forming the curved shape, the bending work is then performed on the raw material subjected to the bending work over a predetermined range from the end of the raw material at a curvature radius smaller than the above curvature radius, and the bending work is subsequently performed over a predetermined range from the end of the raw material so that the curvature radius sequentially becomes smaller. In this art, a plurality of bending rolls having different curvature radii correspond to the curved shape of the medical suturing needle is prepared, and the bending work is sequentially performed by such bending rolls to rationally perform the bending work.
Patent Document 1: Japanese Patent Publication No. 1295902
Patent Document 2: Japanese Patent Publication No. 2002859
Patent Document 3: Japanese Patent Publication No. 3078339